Opening up your network to the Internet poses some inherent risk. Most LANs have some form of security. This security can put some limitations on VoIP applications. Most LAN administrators are aware of the vulnerabilities of their network to attack from the outside. VoIP can operate well in a tight Internet security environment. Multi-site businesses have most likely established a secure data connection between locations making the introduction of VoIP an exercise in bandwidth management. Most successful single site VoIP deployments only use the Internet to connect remote users to the other users in the system. Use of VPNs for remote users is a secure way of connecting all of the users without exposing the network to extreme risk. Use of VPNs also limits outside callers without a VPN connection to using the PSTN to contact users on the system. In some instances, businesses wishing to deploy a large VoIP application using a soft switch where it is not practical to use VPNs, will require additional security.